(1.) Field of the Invention
The present invention relates to coupling devices known as fifth wheels on vehicles wherein the trailer of a tractor trailer vehicle is secured on the bearing surface of the fifth wheel which has a cover plate of a plastic low friction material secured thereto over the entire area of the fifth wheel.
(2.) Description of the Prior Art
Prior structures of this type have utilized bearing plate cover attachments for the reduction of friction on a portion or portions of the fifth wheel bearing plate. See for example U.S. Pat. Nos. 3,924,909, 3,704,924 and 3,337,277.
In U.S. Pat. No. 3,924,909, a sandwich effect is disclosed wherein a metal plate is the bearing surface having a plastic plate between it and the fifth wheel.
The present invention has but a single plastic plate cover secured directly to the fifth wheel of the tractor.
U.S. Pat. No. 3,704,924 discloses a slippery plastic cover over most of the wear area of the bearing plate having a metal forward and rearward edge portion.
The present invention is one continuous sheet of plastic material covering the entire upper portion of the fifth wheel.
In U.S. Pat. No. 3,337,277 a self-lubicating veneer of Teflon is provided for the trailer bearing plate. It does not suggest or show a fifth wheel bearing plate cover as disclosed in the present invention.